This application is related to and claims priority, under 35 U.S.C. xc2xa7 119, from both Japanese Patent Application No. Hei 11-030989, filed on Feb. 9, 1999 and Japanese Patent Application No. Hei 11-353982, filed on Dec. 14, 1999, wherein the entire contents of each above-referenced Japanese Patent Application are hereby incorporated by reference herein.
1. Field of the Invention
The present invention relates to an ink jet printer head to be used, for example, in a printer, a copying machine, or a facsimile device, as well as a method for fabricating the same. Particularly, the invention is concerned with an ink jet printer head capable of being obtained from a single substrate, as well as a method for fabricating the same.
2. Description of the Prior Art
Heretofore, various types of ink jet printer heads utilizing a shear mode of a piezoelectric material have been proposed, including the one disclosed in Japanese Unexamined Patent Publication No. Sho 63-247051. In many of them, however, as pointed out in Japanese Unexamined Patent Publication No. Hei 7-101056, fine grooves serving as pressure chambers are formed by means of a diamond blade and the piezoelectric material typified by PZT (lead zirco-titanate) is ferroelectric. For these reasons, even a portion not concerned in ink jet have a large capacitance, thus giving rise to the problem that the energy efficiency is poor.
In the method disclosed in the aforesaid Japanese Unexamined Patent Publication No. Hei 7-101056, as shown in FIG. 1, a piezoelectric member 2 and a low dielectric member 3 are joined together on a base member 1, further, a top plate 4 and a nozzle plate 5 are joined together, and a large number of grooves are formed to form an ink chamber 6. The portion of each ink chamber 6 located in the piezoelectric member 2 is a portion, a, concerned in ink jet, while the portion thereof located in the low dielectric member 3 is a portion, b, not concerned in ink jet. With this configuration, the capacitance of the portion, b, not taking part in ink jet in the ink chamber 6 is made low to increase the energy efficiency.
Problems involved in such conventional techniques will now be described. In Japanese Unexamined Patent Publication No. Hei 7-101056 there is disclosed nothing about means for obtaining a large number of ink jet printer heads from a single substrate and thus the technique disclosed therein is poor in mass-productivity.
Nor is there found therein any concrete disclosure about how to bond constituent members. Since electrodes are formed within grooves, if air bubbles or the like are formed in adhesive layers, the electrodes may be short-circuited with adjacent elements, or conversely the electrodes may not be connected well on the adhesive layers, which is apt to cause an accident of open circuit.
Further, in such a structure as disclosed in the foregoing Japanese Unexamined Patent Publication No. Hei 7-101056, wherein the piezoelectric member 2 which is movable and the low dielectric member 3 which is not movable are joined together, an adhesive is present in the boundary between the piezoelectric member 2 using a ceramic material or the like and the low dielectric member 3 using an alumina substrate or the like, but as known well, ceramic materials and resins are markedly different in mechanical characteristics such as Young""s modulus, so if variations occur in the thickness of the adhesive, there occur variations in the deformation of the piezoelectric member 2. If the thickness of the adhesive is large, the adhesive serves as a damper and will not obstruct the deformation of the piezoelectric member 2 so greatly, but if it is too small, one end of the piezoelectric member 2 assumes a solid state and obstructs the deformation of the piezoelectric member.
It is an object of the present invention to permit a plurality of ink jet printer heads to be obtained from a single substrate and thereby improve mass-productivity.
It is another object of the present invention to prevent formation of air bubbles in adhesive layers and thereby prevent, upon formation of electrodes within grooves, short-circuit of the electrodes with adjacent elements and prevent the occurrence of an open-circuit accident caused by unsatisfactory connection of the electrodes on the adhesive layers.
It is a further object of the present invention to prevent the occurrence of variations in the deformation of piezoelectric members and thereby improve the print quality.
It is a still further object of the present invention to improve the energy efficiency.
It is a still further object of the present invention to easily form electrodes of a required film thickness within fine grooves.
According to the present invention, in one aspect thereof, there is provided an ink jet printer head fabricating method comprising the steps of joining pre-polarized piezoelectric members so that respective poles are opposed to each other, cutting the thus-joined piezoelectric members into a desired width to form a piezoelectric body, forming a recess for fitting therein of the piezoelectric body in a base member formed of a material different from the material of the piezoelectric members, embedding the piezoelectric body into the recess to form a substrate, forming a plurality of desired grooves in parallel in the piezoelectric body-embedded side of the substrate to form a grooved substrate, forming an electrically conductive film on inner walls of at least the grooves including two such piezoelectric members in the grooved substrate to form a head substrate, making connection to the electrically conductive film for the application of voltage thereto, joining a top plate to the head substrate to form a head substrate-top plate composite, cutting the head substrate-top plate composite at a desired position to form a head, and joining a nozzle plate to a cut side having groove openings of the head.
According to the present invention, in another aspect thereof, there is provided an ink jet printer head fabricating method comprising the steps of cutting two pre-polarized piezoelectric members into a desired width to form a piezoelectric body, forming a recess for fitting therein of the piezoelectric body in a base member formed of a material different from the material of the piezoelectric members, embedding the piezoelectric body into the recess to form a substrate, forming a plurality of desired grooves in parallel in the piezoelectric body-embedded side of the substrate to form a grooved substrate, forming an electrically conductive film on inner walls of at least the grooves in the grooved substrate to form a head substrate, making connection to the electrically conductive film for the application of voltage thereto, joining a top plate to the head substrate to form a head substrate-top plate composite, cutting the head substrate-top plate composite at a desired position to form a head, and joining a nozzle plate to a cut side having groove openings of the head.
According to the present invention, in a further aspect thereof, there is provided an ink jet printer head comprising a head substrate formed by the steps of cutting a pre-polarized piezoelectric member into a desired width to form a piezoelectric body, embedding the piezoelectric body into a recess of a base member formed of a material different from the material of the piezoelectric member to form a substrate, forming a plurality of desired grooves in the piezoelectric body-embedded side of the substrate, and forming an electrically conductive film on inner walls of the grooves; a top plate joined to one side of the head substrate; and a nozzle plate joined to an open side of the grooves, the nozzle plate having ink jet orifices formed respectively for the grooves.
According to the present invention, in a still further aspect thereof, there is provided an ink jet printer head comprising a head substrate formed by the steps of cutting two piezoelectric members into a desired width to form a piezoelectric body, the two piezoelectric members having been joined together so that respective poles are opposed to each other, embedding the piezoelectric body into a recess of a base member formed of a material different from the material of the piezoelectric members to form a substrate, forming a plurality of desired grooves in the piezoelectric body-embedded side of the substrate, and forming an electrically conductive film on inner walls of the grooves including the two piezoelectric members; a top plate joined to one side of the head substrate; and a nozzle plate joined to an open side of the grooves, the nozzle plate having ink jet orifices formed respectively for the grooves.